The present invention pertains to a furnace control method and apparatus for use in controllably increasing the temperature of an analytical furnace in a predictable manner such that specimen gas from different compounds can be separately detected.
During the manufacturing of steel it is necessary to periodically analyze small samples (0.1 to 2 grams) to determine the composition of the melt and particularly the oxygen content thereof. A variety of well-known analyzers are commercially available for providing a quick analysis of such samples providing the total oxygen content contained in a given sample. It is desirable also however to determine from which specific compounds the oxygen is derived. Thus, for example, it is desirable to determine whether the oxygen is eminating from compounds such as FeO, SiO.sub.2, TiO.sub.2, Al.sub.2 O.sub.3, or the like in a steel or cast-iron alloy during the smelting or other stages of steel production.
One system proposed in the prior art is disclosed in German patent application Ser. No. 27 55 587 published on June 21, 1979 in which an optical detector is positioned to receive radiation from the combustion zone and thereby detect the temperature of combustion. The signal from the optical detector is employed for controlling the furnace temperature in a linear fashion at a rate of 20.degree. to 350.degree. centigrade per second. Although such a system will provide separable oxygen peaks for the various oxygen compounds contained in a sample, the temperature sensed by the detector is adversely affected by fusion contaminates such as ash present in the fusion zone. Since the optical window becomes coated with fusion by-products affecting the accuracy of the detected and measured temperature, it is not believed that such a temperature measuring system is practical in the environment of the present invention to achieve accurate and repeatable results.